The attorney general, George Brandis, told the ABC’s Q&A program on Monday night that the Coalition had made a commitment “to repeal section 18C in its current form” – leaving the door open to changing the areas covered by the section rather than removing it entirely.

The director of development and communications at the Institute of Public Affairs, James Paterson, said the entire section 18C was an “excessive limitation on freedom of speech” and should be repealed to keep the spirit of the election promise.

Paterson pointed to Tony Abbott’s comments in December about the Gonski school funding reforms, when the prime minister said the government wanted “to keep our commitments in spirit, as well as in letter”.

“I think that applies in this case,” Paterson said. “They definitely left their supporters who are very passionate about this issue with the impression that they would deal with this and they would repeal it … If they don’t live up to that I think that will amount to a broken promise.”

Brandis told a Senate estimates committee hearing he and Abbott had been careful in their language about the extent of possible changes.

“What I have said and what the prime minister has said is that the government is committed to repealing from the Racial Discrimination Act those provisions which enabled the journalist Andrew Bolt, for example, to be successfully pursued through the courts for expressing an opinion on a matter of public policy,” Brandis said.

“That will involve repealing from section 18C some of the language, but the government has not yet decided on how extensive that legislative amendment will be.”

The race discrimination commissioner, Tim Soutphommasane, said the very next section of the same law ensured artistic works, scientific debate, and fair comment on and fair reporting of a matter of public interest were exempt from being in breach of section 18C, provided it was done reasonably and in good faith.

In a lecture earlier this month, Soutphommasane said the law was working as intended, protecting Australians from “the pernicious harms of racial abuse and harassment”.

He warned a repeal of the section could “license racial hatred” and “unleash a darker, even violent, side of our humanity, which revels in the humiliation of the vulnerable”.

Brandis acknowledged the issue provoked “very strong feelings on both sides of the question”.

He told the Senate estimates committee he had held “careful, far-reaching and sometimes very long discussions with the number of individual community leaders – most particularly, from the ethnic community”. Brandis said the government planned to introduce legislation in the first half of the year which would then be dealt with by a Senate committee.

Last month, in the face of backlash from ethnic minority communities, Brandis told the Australian Jewish News he was considering a separate amendment to the Commonwealth Criminal Code to outlaw racial vilification. He argued this could be done in a way that did not impinge on freedom of speech.

But Paterson said the proposed racial vilification amendment should be opposed because it was a worse proposition than section 18C of the Racial Discrimination Act.

“We’re very concerned about that for a couple of reasons,” he said. “One is you are being held liable for the feelings of other people … they can go to jail for it. Basically you’re being punished for causing someone to commit a thought crime.

“The other perspective is that in the hands of a judge who is not particularly enamoured with free speech a law like that could easily have been used to send Andrew Bolt to jail.”